We propose to carry out foundational studies to characterize the Hepatitis C infectivity of candidate human liver cell transplant products. In order to achieve these studies, we propose to a) assess the HCV infectivity of different fetal and adult liver cell populations, and 2) determine whether shRNA directed against HCV infectivity determinants, such as CD81, can be expressed stably in liver cell populations. PUBLIC HEALTH RELEVANCE: Liver disease is a leading source of mortality in the US. Although liver transplantation is an option for some of patients suffering from liver disease, the scarceness of donor livers makes it difficult for patients to undergo the transplant, and many die waiting for a suitable organ. The transplantation of hepatocytes, rather than whole livers may circumvent many of the limitations of the orthotopic liver transplants. Additionally, almost all of the patients receiving a liver transplant for HCV-associated end-stage liver disease (ESLD) experience re-infection of their graft. Unfortunately, effective anti-HCV therapy for many patients remains elusive. A cell therapy may provide a safe alternative that could be available to more patients. The production of HCV-resistant liver cells will ensure that, upon transplantation, these cells provide the patient not only with the basic liver functions, but also provide an HCV-free liver cell reservoir. In the best case scenario, the liver cells that will be isolated from the healthy organ will be expandable, and HCV-resistant. As the first step in creating these biologically active and transplantable cells, StemCells, Inc. has isolated a population of cells, the human liver engraftable cells (hLECs), that have progenitor/stem cell properties. We propose to use these cells as the starting material, and, in conjunction with shRNA silencing technology, accomplish proof-of-principle studies that will lead to the creation of a transplantable, biologically active, HCV-resistant liver cell product. [unreadable] [unreadable] [unreadable]